1. Field of the Invention:
The present invention relates to a correlation detecting device to detect a correlation of two images.
2. Description of the Prior Art:
Heretofore, as an automatic focus detection device, there has been a device to have images of an object introduced through two different optical paths for detecting an in-focus position out of an amount of deviation in two images thereof. In this case, a correlation detecting device to detect correlation between the two images will become necessary. However, since image signals thereof are analog signals, they are very susceptible to a damage by a transfer, etc., therefore, a number of registers to retain said analog signals need to be provided, which constitute shortcomings of complicating circuits and making sizes thereof larger. Thus, this type of correlation detecting device has A/D converted such analog signals and then processed the same.
However, such device needs to have circuits to make a high speed A/D conversion and a high speed digital operations, resulting in such shortcomings as an increased cost of circuits and increased technical difficulties.